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Xu YangandGreg Kroah-Hartman
d76638353a
commitb84cc80610upstream. When a port is disabled, an attached device will be disconnected. This causes a port-status-change event, which will race with hub autosuspend (if the disabled port was the only connected port on its hub), causing an immediate resume and a second autosuspend. Both of these can be avoided by adding a short delay after the call to usb_hub_set_port_power(). Below log shows what is happening: $ echo 1 > usb1-port1/disable [ 37.958239] usb 1-1: USB disconnect, device number 2 [ 37.964101] usb 1-1: unregistering device [ 37.970070] hub 1-0:1.0: hub_suspend [ 37.971305] hub 1-0:1.0: state 7 ports 1 chg 0000 evt 0002 [ 37.974412] usb usb1: bus auto-suspend, wakeup 1 [ 37.988175] usb usb1: suspend raced with wakeup event <--- [ 37.993947] usb usb1: usb auto-resume [ 37.998401] hub 1-0:1.0: hub_resume [ 38.105688] usb usb1-port1: status 0000, change 0000, 12 Mb/s [ 38.112399] hub 1-0:1.0: state 7 ports 1 chg 0000 evt 0000 [ 38.118645] hub 1-0:1.0: hub_suspend [ 38.122963] usb usb1: bus auto-suspend, wakeup 1 [ 38.200368] usb usb1: usb wakeup-resume [ 38.204982] usb usb1: usb auto-resume [ 38.209376] hub 1-0:1.0: hub_resume [ 38.213676] usb usb1-port1: status 0101 change 0001 [ 38.321552] hub 1-0:1.0: state 7 ports 1 chg 0002 evt 0000 [ 38.327978] usb usb1-port1: status 0101, change 0000, 12 Mb/s [ 38.457429] usb 1-1: new high-speed USB device number 3 using ci_hdrc Then, port change bit will be fixed to the final state and usb_clear_port_feature() can correctly clear it after this period. This will also avoid usb runtime suspend routine to run because usb_autopm_put_interface() not run yet. Fixes:f061f43d74("usb: hub: port: add sysfs entry to switch port power") Cc: stable@kernel.org Signed-off-by: Xu Yang <xu.yang_2@nxp.com> Link: https://patch.msgid.link/20260316095042.1559882-1-xu.yang_2@nxp.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.